Download Holt McDougal Geometry 4-6

4-6 Triangle Congruence: ASA, AAS, and HL
Materials:WARM UP SHEET, Pencil/Pen, TURN
IN HOMEWORK, WS from Yesterday!
GEL 12/1
G: I CAN APPY ASA, AAS AND HL
TO CONSTRUCT TRIANGLES AND
PROVE THEY ARE CONGRUENT.
Warm Up 12/1
What are sides AC and
BC called? Side AB?
E: NOTECATCHER/WS
L: WHITE BOARDS CONGRUENCE
HOMEWORK: NONE!.. FOR NOW
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
An included side is the common side
of two consecutive angles in a polygon.
The following postulate uses the idea of
an included side.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Example 1: Problem Solving Application
A mailman has to collect mail from mailboxes at A
and B and drop it off at the post office at C. Does
the table give enough information to determine the
location of the mailboxes and the post office?
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
1
Understand the Problem
The answer is whether the information in the table
can be used to find the position of points A, B, and C.
List the important information: The bearing from
A to B is N 65° E. From B to C is N 24° W, and from
C to A is S 20° W. The distance from A to B is 8 mi.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
2
Make a Plan
Draw the mailman’s route using vertical lines to show
north-south directions. Then use these parallel lines
and the alternate interior angles to help find angle
measures of ABC.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
3
Solve
mCAB = 65° – 20° = 45°
mCAB = 180° – (24° + 65°) = 91°
You know the measures of mCAB and mCBA and
the length of the included side AB. Therefore by ASA,
a unique triangle ABC is determined.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
4
Look Back
One and only one triangle can be made using the
information in the table, so the table does give
enough information to determine the location of the
mailboxes and the post office.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Check It Out! Example 1
What if……? If 7.6km is the distance from B to C,
is there enough information to determine the
location of all the checkpoints? Explain.
7.6km
Yes; the  is uniquely determined by AAS.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Example 2: Applying ASA Congruence
Determine if you can use ASA to prove the
triangles congruent. Explain.
Two congruent angle pairs are give, but the included
sides are not given as congruent. Therefore ASA
cannot be used to prove the triangles congruent.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Check It Out! Example 2
Determine if you can use ASA to
prove NKL  LMN. Explain.
By the Alternate Interior Angles Theorem. KLN  MNL.
NL  LN by the Reflexive Property. No other congruence
relationships can be determined, so ASA cannot be
applied.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
You can use the Third Angles Theorem to prove
another congruence relationship based on ASA. This
theorem is Angle-Angle-Side (AAS).
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Example 3: Using AAS to Prove Triangles Congruent
Use AAS to prove the triangles congruent.
Given: X  V, YZW  YWZ, XY  VY
Prove:  XYZ  VYW
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Check It Out! Example 3
Use AAS to prove the triangles congruent.
Given: JL bisects KLM, K  M
Prove: JKL  JML
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Example 4A: Applying HL Congruence
Determine if you can use the HL Congruence
Theorem to prove the triangles congruent. If
not, tell what else you need to know.
According to the diagram,
the triangles are right
triangles that share one
leg.
It is given that the
hypotenuses are
congruent, therefore the
triangles are congruent by
HL.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Example 4B: Applying HL Congruence
This conclusion cannot be proved by HL. According
to the diagram, the triangles are right triangles and
one pair of legs is congruent. You do not know that
one hypotenuse is congruent to the other.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Check It Out! Example 4
Determine if you can use
the HL Congruence Theorem
to prove ABC  DCB. If
not, tell what else you need
to know.
Yes; it is given that AC  DB. BC  CB by the
Reflexive Property of Congruence. Since ABC
and DCB are right angles, ABC and DCB are
right triangles. ABC  DCB by HL.
Holt McDougal Geometry
4-6 Triangle Congruence: ASA, AAS, and HL
Materials:WARM UP SHEET, Pencil/Pen, TURN
IN EXTRA CREDIT, WS with theorems
GEL 12/2
G: I CAN APPY SSS, SAS, ASA, AAS
AND HL TO CONSTRUCT
TRIANGLES AND PROVE THEY
ARE CONGRUENT.
NO WARM UP TODAY. I’LL
COLLECT THEM IN 8
MINUTES! MAKE SURE YOU
HAVE ALL 4 FROM THIS
WEEK!
E: NOTECATCHER/WS
L: KAHOOT!
HOMEWORK: NONE!.. FOR NOW
Holt McDougal Geometry